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In refuting an Indonesian Islamic council finding to the contrary,

AstraZeneca Indonesia director Rizman Abudaeri said in a statement: “At all stages of the production process, this virus vector vaccine does not use nor come in contact with pork-derived products or other animal products.”

I find the last bit of that statement somewhat hard to believe because e.g. the FDA noted in 2018 that:

Although synthetic media have been developed for growth of many medically important microorganisms, some still require additional nutrients which are easily provided by animal-derived products such as serum and blood. Viral vaccines are produced in living cells, which, similarly, require the addition of complex growth media components, such as fetal calf serum. [...] Cow components are often used simply because cows are very large animals, commonly used for food, and thus much material is available. Animal-derived products used in vaccine manufacture can include amino acids, glycerol, detergents, gelatin, enzymes and blood. Cow milk is a source of amino acids, and sugars such as galactose. Cow tallow derivatives used in vaccine manufacture include glycerol. Gelatin and some amino acids come from cow bones. Cow skeletal muscle is used to prepare broths used in certain complex media. Many difficult to grow microorganisms and the cells that are used to propagate viruses require the addition of serum from blood to the growth media.

So, is there more info available on how AZ grows their vaccine to support that summary statement that it doesn't come in contact with any animal products (unlike quite a few similar virus-vectored vaccines)?

After a bit more searching, it seems AZ uses HEK293 cells to grow their adenovirus... but according to a 2013 paper a way to grow these cells involved two products that are animal-free according to their manufacturers (SFMTransFx-293 and GlutaMAX) but also 5% v/v "FBS", which almost certainly means fetal bovine serum, in this context. Another paper substitutes those first two substances with DMEM, but still uses 10% FBS. This doesn't excluded that may also grow without FBS or in some other process though.

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In the European Assessment Report for the AstraZeneca, they make that statement more specifically:

The applicant also confirmed that no material of human or animal origin are used in the growth medium or feed (including no materials manufactured with animal-derived material). No materials of human origin other than the T- REx-293 cells themselves were used in the host cell line culture, virus seed development, preparation of the host cell banks and AZD1222 virus seeds, or AS manufacturing process.

they go on to state that

Several materials of animal or other biological origin are used in the current manufacturing process and were used in the development and manufacture of the cell banks and the virus seeds. Nuclease is the only raw material of animal origin used in the AZD1222 manufacturing process. One specified material of animal origin was used in the preparation of cell banks and virus seed banks. Several materials of animal origin were used in the development of vector construct and pre-GMP cell bank. Reference is made to the Adventitious agents section for detailed information. Certificates of analysis and/or certificates of origin as well as certificates of suitability with regards to TSE (when relevant) are included

I haven't been able to track down exactly how FBS was removed - perhaps these 293s are transgenic anyway; but as far as I can see, the same report specifies a very good reason why they spent the effort to remove the FBS: it was causing a safety signal:

There was a reaction upon challenge observed in some animals in the first study (20-01125), that the Applicant ascribes to presence of BSA in the challenge virus stock. The probable root cause of this adverse event was identified as a medium component, foetal bovine serum (FBS). Ferret sera were shown to have significant levels of antibodies reacting to a component of the FBS (BSA).


Development and improvement of a serum-free suspension process for the production of recombinant adenoviral vectors using HEK293 cells, 2001, Tsao et al, appears to have been an early report in this field. They state that:

The serum-free suspension process is often the preferred mode of production due to its potential ease in scale-up operation, simplicity in downstream processing and reduced risk of virus contamination. The HEK293 cell and its derivatives, however, have a tendency to form for the expression of recombinant proteins by inlarge cell aggregates in suspension culture

Surprisingly, contrary to my expectation, the FBS-free technique described does not appear to require any transgenes to be expressed; instead, it is simply one of careful medium supplementation and slow, deliberate weaning.

293 cells used for adenovirus production are often of the complementary E-deleted variety; that is, they have likely already been modified to express the virus' E1 protein. With that in mind, it's not much of a stretch to imagine further modifications for serum adaptation, but that doesn't seem to be the case.

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    I saw that (final part), but that was in a animal test. There's little reason to think people would have had that reaction anyway even if FBS were used. "This can be a result of the pre-existence of anti-BSA antibodies derived from the required husbandry vaccination."
    – Fizz
    Oct 3, 2021 at 3:49
  • @Fizz I guess. Here's someone saying researchgate.net/post/… they were able to culture 293 in "FreeStyle293 Expression Medium from Gibco"
    – 0xDBFB7
    Oct 3, 2021 at 3:51
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    It looks like Sputnik V is using FBS though (to grow it)... so as I suspected this is a fairly new development for large scale production doing away with FBS entirely... which is probably why AZ don't want to say a whole lot more in public as to what exactly they are using.
    – Fizz
    Oct 3, 2021 at 3:59
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    Serum free HEK suspension culture has been pretty routine for a long time now. It's a combination of the important stuff from serum made recombinantly from bacteria and adapting the line to grow without the less important stuff from FBS.
    – CJR
    Oct 3, 2021 at 21:16
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    Honestly I think your answer is already good. Here's a reference for serum free adaptation if you're interested in reading about it (it's a classic) doi.org/10.1016/0092-8674(80)90540-1
    – CJR
    Oct 3, 2021 at 21:45

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